Push-button tuning with band-width control



Aug. 12, 1941. W. RGHR 2,252,098

PUSH-BUTTON TUNING WITH BAND-WIDTH CONTROL Filed Nov. 9, 1939 Enventor Patented Aug. 12, 1941 UNIT STT rrr rrics PUSH-BUTTON TUNING WITH BAND-WIDTH CONTROL ,Application November 9, 1939, Serial No. 303,595 In Germany November 9, 1938 4 Claims.

Band-width variation in broadcast receivers serves the purpose to alter the selection of the apparatus at will. Variation ofiers the advantage that stations whose signals come in very strong, more particularly local transmitters, when the regulator knob is set on broad band may be heard without cutting off the audio frequenciesand also with greater volume. It will be remembered that by constricting the RF pass band, the AF band becomes of less width and the volume is diminished.

When a receiver set is equipped with push button tuning means so that the desired station is tuned in automatically by actuation of push buttons, only stations will be selected which give good reception locally. But these, in most cases, are only those stations which come in with a powerful signal. Hence, for these no curtailing of the RF band to raise the selectivity is necessary.

The invention suggests that in receiver sets with band-width variation, means should be provided (say, a cord. drive or switches) which, when actuating any one of the push buttons, will cause the band-width variation means to assume the position of maximum band or a band which is adapted to the particular station so selected. The quality of reception is improved and the stations will come in slightly more loud. The invention will now be explained with reference to the accompanying drawing in which Fig. 1 is a modification whereby band-width control incidental with tuning is accomplished through mechanical means, Fig. 2 is a modification useful for varying the band-width by electrical means, and Fig. 3 shows an i. f. filter circuit capable of use in conjunction with Fig. 2.

Referring now to Fig. 1 the push buttons, only two of which are here disclosed, are represented by the numeral I. Operation of any one of the push buttons will in a known manner adjust the tuning mechanism (not shown) to a preselected station and at the same time will cause the depending lug 2 to rock the cradle 3 about its pivoted members 4, 4. A cable 5 is attached at one end to the cradle, is then entrained about the pulley 6, and finally is wound for a few turns around the drum I, to which the opposite end of the cable 5 is aflixed. The drum 1 is loosely mounted on a band-width control shaft 8 which is adapted to control the band-width device 9 shown in block. The opposite end of the control shaft is provided with a knob It! for manual control, the index of the knob showing the respective positions for sharp and broad tuning.

The drum 1 is provided with a peg I l which normally, due to the tension of the spring 12, abuts against the stop member l3. The control shaft 8 also is provided with a peg I 2 which is adapted to cooperate with peg ll of the drum.

Upon actuation of a push button I the drum 1 will tend to rotate in the direction indicated by the arrow, and consequently through coaction between pegs II and I2 the shaft 8 will rotate in a direction to suitably adjust the band-width device 9. The lugs 2 of the push buttons are each preferably adjustable in the direction of operation 50 that for the station to be tuned corresponding to a particular push button, the appropriate band width adjustment may be had.

In order that each push-button will retain its position of operation a locking bar I6 pivoted at ll engages the notch 18 in the push button, and upon actuation of another push button the locking bar is released from the prior operated push button to engage the notch of the subsequent push button, in a known manner.

In Fig. 2 the locking bar It is provided with a cam member l'l' arranged to actuate a switch having the three blades X, B and S which correspond to the elements similarly indicated in Fig. 3. With the blade X in its lower position, the auxiliary winding W is disconnected and the circuits I and II which constitute the usual i. f. portion of a superheterodyne receiver will be loosely coupled to provide sharp selectivity. With the center blade X in the upper position, the auxiliary winding W will be included in circuit I causing close coupling between the circuits I and II resulting in the transmission of a broad band of frequencies, or high fidelity transmission.

As previously mentioned, the push buttons are ordinarily assigned to local stations providing good reception, so that sharp selectivity is not an important factor with push button tuning. However, in tuning in distant stations by means of the manual tuning member it is desirable that the circuits I and II, for example, or those in.

the RF stage, be adjusted to sharp selectivity. This is brought about when all the push buttons are in their normal or inoperative positions. The locking bar 16 will as a result he in a position to permit contact between blades X and S so that the circuits are adjusted for sharp selectivity. Upon operation of a push button the blade X will break contact with S and make contact with the upper blade B thereby cutting into circuit the third winding W so that the circuits are conditioned for the transmission of a wide band.

It will be understood that there are other ways and means for carrying the basic idea into practice, say, by cutting in circuit larger coupling capacitors between two filters and the like, for variation of the band-width.

What I claim is:

1. In a push-button receiver of the type provided with an operating member for each of a plurality of predetermined stations, means for adjusting the selectivity of the receiver, a pivoted member under the control of all said operating members, and connecting means between said pivoted member and the selectivity adjusting means, said pivoted member being actuated by any one of said operating members and, through the connecting means, adapted to adjust the selectivity adjusting means in a predetermined manner.

2. In a push-button receiver of the type provided with an operating member for each of a plurality of predetermined stations, means including a control shaft for adjusting the selectivity of the receiver, a pivoted rocker member under the control of all said operating members, a cable interconnecting the rocker member and the control shaft, and means carried by each operating member which upon actuation is adapted to move the rocker member and incidently the control shaft whereby adjustment of the selectivity adjusting means is brought about in a predetermined manner.

3. In a push-button receiver of the type provided with an operating member for each of a plurality of predetermined stations, means including a control shaft for adjusting the selectivity of the receiver, a bushing loosely mounted on said control shaft, spring means for urging said bushing to a limiting position by having a pin carried by the bushing abut a stop member, a pivoted rocker member under the control of all said operating members, a cable interconnecting the rocker member and the bushing, means carried by each operating member which upon actuation is adapted to move the rocker member and incidently the bushing against the action of the spring means, and a pin carried by the control shaft adapted to coact with the pin on the bushing, whereby the selectivity adjusting means is controlled in a predetermined manner.

4. In a push-button receiver of the type provided with an operating member for each of a plurality of predetermined stations, said receiver having a pair of coupled circuits one of which is provided with an auxiliary winding, the action of Which is to cause said coupled circuits to be loosely or tightly coupled thereby providing sharp selectivity or high fidelity depending upon whether the auxiliary winding is inactive or active respectively, switch means interposed between said winding and its associated circuit and in normal position causing said winding to be inactive, and common means under the control of all said operating members and controlled by any one of said members upon actuation thereof for operating the switch means to cause said auxiliary winding to become active.

WALTER RGHR. 

